APN after rooting - cannot save data?

I followed all the instructions on rooting so I could remove the sim network lock, but after this was successful, I have no apn.

I've tried manually adding the T-Mobile uk settings, but when I click on save apn it does not show on the apn screen?

I've looked in the XML document in the etc folder using rootplus, and it shows all sorts of info including something from T-Mobile uk, but none of these show on the apn screen, and they are quite different fom the apn data I've seen on the web.